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Posted to dev@mina.apache.org by "Andrew C (JIRA)" <ji...@apache.org> on 2013/01/30 21:21:13 UTC

[jira] [Created] (SSHD-207) CLONE - Direct TCP/IP Port Forward sends EOF to client after closing channel

Andrew C created SSHD-207:
-----------------------------

             Summary: CLONE - Direct TCP/IP Port Forward sends EOF to client after closing channel
                 Key: SSHD-207
                 URL: https://issues.apache.org/jira/browse/SSHD-207
             Project: MINA SSHD
          Issue Type: Bug
    Affects Versions: 0.6.0
            Reporter: Andrew C
            Assignee: Guillaume Nodet
             Fix For: 0.7.0


While testing port forwarding from an OpenSSH_5.8p2 client to a MINA SSHD server, I noticed that after the first disconnection of a client from the forwarded port, the entire SSH session would be disconnected.  The client command I ran was:

ssh -N -L 60443:<target>:443 -p 50022 tester@<minasshd>

Looking at the traces, I saw the following from SSHD:


13:54:12.823 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - Received packet SSH_MSG_CHANNEL_OPEN
13:54:12.823 [NioProcessor-1] INFO  o.a.s.server.session.ServerSession - Received SSH_MSG_CHANNEL_OPEN direct-tcpip
13:54:12.826 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Receiving request for direct tcpip: hostToConnect=<target>, portToConnect=443, originatorIpAddress=127.0.0.1, originatorPort=54145
13:54:15.588 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - Received packet SSH_MSG_CHANNEL_EOF
13:54:15.589 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Received SSH_MSG_CHANNEL_EOF on channel 0
13:54:15.589 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Send SSH_MSG_CHANNEL_CLOSE on channel 0
13:54:15.590 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - Received packet SSH_MSG_CHANNEL_CLOSE
13:54:15.590 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Received SSH_MSG_CHANNEL_CLOSE on channel 0
13:54:15.590 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Closing channel 0 immediately
13:54:15.591 [NioProcessor-1] INFO  o.a.s.s.channel.ChannelDirectTcpip - Closing channel 0 immediately
13:54:15.593 [NioProcessor-26] INFO  o.a.s.s.channel.ChannelDirectTcpip - Send SSH_MSG_CHANNEL_EOF on channel 0
13:54:15.595 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - Received packet SSH_MSG_DISCONNECT
13:54:15.595 [NioProcessor-1] INFO  o.a.s.server.session.ServerSession - Received SSH_MSG_DISCONNECT (reason=2, msg=Received ieof for nonexistent channel 2.)
13:54:15.595 [NioProcessor-1] INFO  o.a.s.server.session.ServerSession - Closing session
13:54:15.595 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - Closing IoSession
13:54:15.596 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession - IoSession closed

So if I read this right, the client sends an EOF, then the server sends a CLOSE, then the client sends a CLOSE.  After all of this, the server sends back an EOF, but the channel no longer exists at the client, which causes a disconnection.

I looked into the source code, and figured the following change might correct the issue:

Index: sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java
===================================================================
--- sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java	(revision 1207930)
+++ sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java	(working copy)
@@ -109,7 +109,9 @@
 
             @Override
             public void sessionClosed(IoSession session) throws Exception {
+               if (!closing) {
                 sendEof();
+               }
             }
         };
         connector.setHandler(handler);

It appears to work, but I do not know if it is correct, or if it will break other situations.  Can anyone comment on it?

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